We Already Lost Our Most Valuable Secret Weapon

Tropical rainforests, once thought to be climate change buffers, are experiencing rising temperatures, threatening biodiversity and highlighting the urgent need for conservation

I love scientific conferences. Well, not all the time. They sometimes really overwhelm me, with so many people initiating interactions. But there’s something that I always encounter in every conference I attend: fascinating people with fascinating stories.

Suddenly, scientists stopped being the name behind a publication and became a face or even a legend of scientific adventure and exploration.

At one of these conferences, I was honored to meet a scientist who grew up in the Amazon rainforest. She told me about waking up to howler monkeys’ calls and tropical birds’ hues. In her opinion, her life took exactly what she was destined to do. Her fascination with the forest led her to become a conservation scientist, dedicated to preserving the environment that nurtured her childhood curiosity.

Years later, as she navigated through the dense undergrowth on a research expedition, she noticed subtle but alarming changes. It wasn’t cool anymore under the canopy; it was becoming warmer. We inquired whether someone would eventually study this phenomenon.

A recent study published in Nature Climate Change confirmed her suspicions. Long-term data collected from temperature loggers indicate that rainforest microclimates are shifting.

Tropical rainforests, the world’s most diverse ecosystems, are facing a new and growing threat: rising temperatures beneath their canopies. For years, it was believed that the dense canopy of tropical forests provided a buffer against the impacts of climate change, especially warming and droughts. However, new research indicates that this assumption might no longer hold. While extremely powerful, tropical rainforests may also have their limits.

The study, led by Dr. Brittany Trew from the Royal Society for the Protection of Birds, used a microclimate model to examine temperatures under the rainforest canopy across the global tropics from 2005 to 2019. The results are alarming: most of the world’s undisturbed tropical forests, thus which are theoretically off limits from human impacts, experienced climate conditions outside their historical ranges. In many areas, temperatures have shifted to almost entirely new averages. In other words, they now have new “normals.”

Dr. Trew explains, “Our research shows that climate change already impacts vast areas of pristine tropical forest globally. To provide species the best chance to adapt to these changes, these forests must be protected from additional human-induced threats.”

Tropical forests are home to countless species that have evolved within a narrow range of temperatures. This evolutionary history makes them particularly vulnerable to even small climate changes. They simply aren’t adapted to anything outside these ranges. However, as the study found, many areas have already transitioned to new temperature regimes, leaving wildlife poorly adapted to cope.

Dr. David Edwards from the University of Cambridge’s Department of Plant Sciences, a study co-author, emphasizes the stakes: “Tropical forests are the true powerhouses of global biodiversity, and the complex networks of species they contain underpin vast carbon stocks that help mitigate climate change. A severe risk is that species can no longer survive within tropical forests as climate change intensifies, further exacerbating the global extinction crisis and degrading rainforest carbon stocks.”

Recent observations in largely undisturbed tropical forests support these findings. Changes in species composition (the type of plants and animals we find in a particular place) and significant declines in animal, insect, and plant populations have been documented. The culprit? Most likely the warming temperatures.

The study’s findings align with these trends, indicating that the impact of rising temperatures goes beyond populated areas and their surroundings. They can be felt Everywhere. Even in places no person has ever stepped in.

But these are worse news than you may think. The belief that tropical forest canopies could shield the understory from climate extremes has been a cornerstone of conservation thinking. Most saw it as our last resource, our secret weapon.

However, the new research challenges this notion. Dr. Alexander Lees from Manchester Metropolitan University, another co-author, notes, “Our study challenges the prevailing notion that tropical forest canopies will mitigate climate change impacts and helps us understand how to prioritize conservation of these key areas of biodiversity effectively.”

One of the study’s critical insights is identifying regions that have maintained relatively stable climates. For example, parts of the Guiana Shield and the southwestern Amazon have experienced climate conditions similar to historical baselines, indicating that the effects there are not yet alarming. Although they could be shortly.

Given the findings, the study’s researchers call for a reassessment of conservation priorities. Protecting areas that serve as climate refugia is a crucial first step. These regions provide a refuge for species that might not survive in more rapidly changing environments. However, protection alone is not enough. Restoration efforts are also vital to enhance the resilience of these ecosystems. To ensure that these species have somewhere to move to.

Further, Dr. Lees stresses the importance of addressing the broader drivers of deforestation and degradation: “It is paramount that distant, wealth-related drivers of deforestation and degradation are addressed and that the future of those forests acting as climate refuges is secured by effecting legal protection, and by empowering indigenous communities.”

The study underscores the interconnectedness of global conservation efforts. While local actions are crucial, they must be supported by broader initiatives to reduce carbon emissions and mitigate climate change on a global scale. One won’t take us anywhere if we don’t work on the other. Further, empowering Indigenous communities and ensuring their involvement in conservation strategies is also key to protecting these vital ecosystems.

Dr. Trew and her colleagues highlight the urgency of these efforts: “To provide species with the best chance to adapt to these changes, these forests must be protected from additional human-induced threats.” This means halting deforestation and implementing strategies that enhance the resilience of tropical forests to climate change. It means looking at conservation from a holistic perspective.

The findings of this study offer a reality check, a reminder of the challenges we face in conserving the world’s most diverse ecosystems. Tropical forests, with their intricate web of life and critical role in regulating the planet’s climate, are threatened by rising temperatures. The time to act is now.

In the words of the late Dr. Thomas Lovejoy, a pioneering conservation biologist, “The future of the earth’s biodiversity depends on the actions we take today.” Protecting tropical forests and ensuring they continue serving as biodiversity refuges is a global imperative. We must address local and global threats to safeguard these vital ecosystems for future generations.

The research is clear: tropical forests are less insulated from climate change than previously thought. And we can’t afford to lose them. It’s up to us to respond to this challenge with urgency and commitment, ensuring that these incredible reservoirs of biodiversity remain resilient in the face of a changing climate.